diff mbox series

[28/44] unify the rest of iov_iter_get_pages()/iov_iter_get_pages_alloc() guts

Message ID 20220622041552.737754-28-viro@zeniv.linux.org.uk (mailing list archive)
State New, archived
Headers show
Series [01/44] 9p: handling Rerror without copy_from_iter_full() | expand

Commit Message

Al Viro June 22, 2022, 4:15 a.m. UTC 
same as for pipes and xarrays; after that iov_iter_get_pages() becomes
a wrapper for __iov_iter_get_pages_alloc().

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
 lib/iov_iter.c | 86 ++++++++++++++++----------------------------------
 1 file changed, 28 insertions(+), 58 deletions(-)

Comments

Jeff Layton June 28, 2022, 11:54 a.m. UTC | #1 
On Wed, 2022-06-22 at 05:15 +0100, Al Viro wrote:
> same as for pipes and xarrays; after that iov_iter_get_pages() becomes
> a wrapper for __iov_iter_get_pages_alloc().
> 
> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
> ---
>  lib/iov_iter.c | 86 ++++++++++++++++----------------------------------
>  1 file changed, 28 insertions(+), 58 deletions(-)
> 
> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> index 07dacb274ba5..811fa09515d8 100644
> --- a/lib/iov_iter.c
> +++ b/lib/iov_iter.c
> @@ -1372,20 +1372,19 @@ static struct page *first_bvec_segment(const struct iov_iter *i,
>  	return page;
>  }
>  
> -ssize_t iov_iter_get_pages(struct iov_iter *i,
> -		   struct page **pages, size_t maxsize, unsigned maxpages,
> -		   size_t *start)
> +static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
> +		   struct page ***pages, size_t maxsize,
> +		   unsigned int maxpages, size_t *start)
>  {
>  	size_t len;
>  	int n, res;
>  
>  	if (maxsize > i->count)
>  		maxsize = i->count;
> -	if (!maxsize || !maxpages)
> +	if (!maxsize)
>  		return 0; 
>  	if (maxsize > MAX_RW_COUNT)
>  		maxsize = MAX_RW_COUNT;
> -	BUG_ON(!pages);
>  
>  	if (likely(user_backed_iter(i))) {
>  		unsigned int gup_flags = 0;
> @@ -1398,80 +1397,51 @@ ssize_t iov_iter_get_pages(struct iov_iter *i,
>  
>  		addr = first_iovec_segment(i, &len, start, maxsize, maxpages);
>  		n = DIV_ROUND_UP(len, PAGE_SIZE);
> -		res = get_user_pages_fast(addr, n, gup_flags, pages);
> +		if (!*pages) {
> +			*pages = get_pages_array(n);
> +			if (!*pages)
> +				return -ENOMEM;
> +		}
> +		res = get_user_pages_fast(addr, n, gup_flags, *pages);
>  		if (unlikely(res <= 0))
>  			return res;
>  		return (res == n ? len : res * PAGE_SIZE) - *start;
>  	}
>  	if (iov_iter_is_bvec(i)) {
> +		struct page **p;
>  		struct page *page;
>  
>  		page = first_bvec_segment(i, &len, start, maxsize, maxpages);
>  		n = DIV_ROUND_UP(len, PAGE_SIZE);
> +		p = *pages;
> +		if (!p) {
> +			*pages = p = get_pages_array(n);
> +			if (!p)
> +				return -ENOMEM;
> +		}
>  		while (n--)
> -			get_page(*pages++ = page++);
> +			get_page(*p++ = page++);
>  		return len - *start;
>  	}
>  	if (iov_iter_is_pipe(i))
> -		return pipe_get_pages(i, &pages, maxsize, maxpages, start);
> +		return pipe_get_pages(i, pages, maxsize, maxpages, start);
>  	if (iov_iter_is_xarray(i))
> -		return iter_xarray_get_pages(i, &pages, maxsize, maxpages, start);
> +		return iter_xarray_get_pages(i, pages, maxsize, maxpages,
> +					     start);
>  	return -EFAULT;
>  }
> -EXPORT_SYMBOL(iov_iter_get_pages);
>  
> -static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
> -		   struct page ***pages, size_t maxsize,
> +ssize_t iov_iter_get_pages(struct iov_iter *i,
> +		   struct page **pages, size_t maxsize, unsigned maxpages,
>  		   size_t *start)
>  {
> -	struct page **p;
> -	size_t len;
> -	int n, res;
> -
> -	if (maxsize > i->count)
> -		maxsize = i->count;
> -	if (!maxsize)
> +	if (!maxpages)
>  		return 0;
> -	if (maxsize > MAX_RW_COUNT)
> -		maxsize = MAX_RW_COUNT;
> -
> -	if (likely(user_backed_iter(i))) {
> -		unsigned int gup_flags = 0;
> -		unsigned long addr;
> -
> -		if (iov_iter_rw(i) != WRITE)
> -			gup_flags |= FOLL_WRITE;
> -		if (i->nofault)
> -			gup_flags |= FOLL_NOFAULT;
> -
> -		addr = first_iovec_segment(i, &len, start, maxsize, ~0U);
> -		n = DIV_ROUND_UP(len, PAGE_SIZE);
> -		*pages = p = get_pages_array(n);
> -		if (!p)
> -			return -ENOMEM;
> -		res = get_user_pages_fast(addr, n, gup_flags, p);
> -		if (unlikely(res <= 0))
> -			return res;
> -		return (res == n ? len : res * PAGE_SIZE) - *start;
> -	}
> -	if (iov_iter_is_bvec(i)) {
> -		struct page *page;
> +	BUG_ON(!pages);
>  
> -		page = first_bvec_segment(i, &len, start, maxsize, ~0U);
> -		n = DIV_ROUND_UP(len, PAGE_SIZE);
> -		*pages = p = get_pages_array(n);
> -		if (!p)
> -			return -ENOMEM;
> -		while (n--)
> -			get_page(*p++ = page++);
> -		return len - *start;
> -	}
> -	if (iov_iter_is_pipe(i))
> -		return pipe_get_pages(i, pages, maxsize, ~0U, start);
> -	if (iov_iter_is_xarray(i))
> -		return iter_xarray_get_pages(i, pages, maxsize, ~0U, start);
> -	return -EFAULT;
> +	return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start);
>  }
> +EXPORT_SYMBOL(iov_iter_get_pages);
>  
>  ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
>  		   struct page ***pages, size_t maxsize,
> @@ -1481,7 +1451,7 @@ ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
>  
>  	*pages = NULL;
>  
> -	len = __iov_iter_get_pages_alloc(i, pages, maxsize, start);
> +	len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start);
>  	if (len <= 0) {
>  		kvfree(*pages);
>  		*pages = NULL;

Reviewed-by: Jeff Layton <jlayton@kernel.org>
diff mbox series

Patch

diff --git a/lib/iov_iter.c b/lib/iov_iter.c
index 07dacb274ba5..811fa09515d8 100644
--- a/lib/iov_iter.c
+++ b/lib/iov_iter.c
@@ -1372,20 +1372,19 @@  static struct page *first_bvec_segment(const struct iov_iter *i,
 	return page;
 }
 
-ssize_t iov_iter_get_pages(struct iov_iter *i,
-		   struct page **pages, size_t maxsize, unsigned maxpages,
-		   size_t *start)
+static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
+		   struct page ***pages, size_t maxsize,
+		   unsigned int maxpages, size_t *start)
 {
 	size_t len;
 	int n, res;
 
 	if (maxsize > i->count)
 		maxsize = i->count;
-	if (!maxsize || !maxpages)
+	if (!maxsize)
 		return 0;
 	if (maxsize > MAX_RW_COUNT)
 		maxsize = MAX_RW_COUNT;
-	BUG_ON(!pages);
 
 	if (likely(user_backed_iter(i))) {
 		unsigned int gup_flags = 0;
@@ -1398,80 +1397,51 @@  ssize_t iov_iter_get_pages(struct iov_iter *i,
 
 		addr = first_iovec_segment(i, &len, start, maxsize, maxpages);
 		n = DIV_ROUND_UP(len, PAGE_SIZE);
-		res = get_user_pages_fast(addr, n, gup_flags, pages);
+		if (!*pages) {
+			*pages = get_pages_array(n);
+			if (!*pages)
+				return -ENOMEM;
+		}
+		res = get_user_pages_fast(addr, n, gup_flags, *pages);
 		if (unlikely(res <= 0))
 			return res;
 		return (res == n ? len : res * PAGE_SIZE) - *start;
 	}
 	if (iov_iter_is_bvec(i)) {
+		struct page **p;
 		struct page *page;
 
 		page = first_bvec_segment(i, &len, start, maxsize, maxpages);
 		n = DIV_ROUND_UP(len, PAGE_SIZE);
+		p = *pages;
+		if (!p) {
+			*pages = p = get_pages_array(n);
+			if (!p)
+				return -ENOMEM;
+		}
 		while (n--)
-			get_page(*pages++ = page++);
+			get_page(*p++ = page++);
 		return len - *start;
 	}
 	if (iov_iter_is_pipe(i))
-		return pipe_get_pages(i, &pages, maxsize, maxpages, start);
+		return pipe_get_pages(i, pages, maxsize, maxpages, start);
 	if (iov_iter_is_xarray(i))
-		return iter_xarray_get_pages(i, &pages, maxsize, maxpages, start);
+		return iter_xarray_get_pages(i, pages, maxsize, maxpages,
+					     start);
 	return -EFAULT;
 }
-EXPORT_SYMBOL(iov_iter_get_pages);
 
-static ssize_t __iov_iter_get_pages_alloc(struct iov_iter *i,
-		   struct page ***pages, size_t maxsize,
+ssize_t iov_iter_get_pages(struct iov_iter *i,
+		   struct page **pages, size_t maxsize, unsigned maxpages,
 		   size_t *start)
 {
-	struct page **p;
-	size_t len;
-	int n, res;
-
-	if (maxsize > i->count)
-		maxsize = i->count;
-	if (!maxsize)
+	if (!maxpages)
 		return 0;
-	if (maxsize > MAX_RW_COUNT)
-		maxsize = MAX_RW_COUNT;
-
-	if (likely(user_backed_iter(i))) {
-		unsigned int gup_flags = 0;
-		unsigned long addr;
-
-		if (iov_iter_rw(i) != WRITE)
-			gup_flags |= FOLL_WRITE;
-		if (i->nofault)
-			gup_flags |= FOLL_NOFAULT;
-
-		addr = first_iovec_segment(i, &len, start, maxsize, ~0U);
-		n = DIV_ROUND_UP(len, PAGE_SIZE);
-		*pages = p = get_pages_array(n);
-		if (!p)
-			return -ENOMEM;
-		res = get_user_pages_fast(addr, n, gup_flags, p);
-		if (unlikely(res <= 0))
-			return res;
-		return (res == n ? len : res * PAGE_SIZE) - *start;
-	}
-	if (iov_iter_is_bvec(i)) {
-		struct page *page;
+	BUG_ON(!pages);
 
-		page = first_bvec_segment(i, &len, start, maxsize, ~0U);
-		n = DIV_ROUND_UP(len, PAGE_SIZE);
-		*pages = p = get_pages_array(n);
-		if (!p)
-			return -ENOMEM;
-		while (n--)
-			get_page(*p++ = page++);
-		return len - *start;
-	}
-	if (iov_iter_is_pipe(i))
-		return pipe_get_pages(i, pages, maxsize, ~0U, start);
-	if (iov_iter_is_xarray(i))
-		return iter_xarray_get_pages(i, pages, maxsize, ~0U, start);
-	return -EFAULT;
+	return __iov_iter_get_pages_alloc(i, &pages, maxsize, maxpages, start);
 }
+EXPORT_SYMBOL(iov_iter_get_pages);
 
 ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 		   struct page ***pages, size_t maxsize,
@@ -1481,7 +1451,7 @@  ssize_t iov_iter_get_pages_alloc(struct iov_iter *i,
 
 	*pages = NULL;
 
-	len = __iov_iter_get_pages_alloc(i, pages, maxsize, start);
+	len = __iov_iter_get_pages_alloc(i, pages, maxsize, ~0U, start);
 	if (len <= 0) {
 		kvfree(*pages);
 		*pages = NULL;